User instructions for the soft universal etching ground Graphic Chemical.
Sorry, not in Spanish yet....
The plate must be covered with a thin layer of ground. It is very important that this ground is applied correctly, since a bad ground can distroy all the work being done. A thin ground will bite through very quickly at the wrong locations. If the ground is too thick, the varnish might crumble off at cross-hatchings. This also happens if the ground is burnt too much: if overheated, the ground becomes brittle.
If a line is drawn with a needle, through a thicker part of the ground, the acid meets more resistance in the thicker part, making the lines thinner and less deep. In a section of the prints with many lines, a clear distinction can be made between the thinner and the thicker ground. A print will also show it clearly. For this reason, an even distribution of the ground is very important. Dust is the grounds major enemy: around particles of dust the varnish seems to be thinner. Under a magnifier, this shows clearly. A particle of dust is surrounded by only a quarter of the normal quantity of ground. The acid will penetrate easily, creating dozens of litlle holes. In the resulting print, this is not always visible, but it is quite difficult to remove these spots when they do appear.
If a liquid ground is applied to the plate, heating the plate is not required. The plate is positioned on its side (tilted), and some liquid from the bottle is poured on to a saucer. It should flow easily. If it is too thick, dilute it with naphtha. It should not be too thin, otherwise the acid will break through too easily. With a dust-free brush, apply the ground onto the plate, striking from top to bottom. Dust is even more a problem than with solid hard ground.
A simple way is the following: rest the plate on the fingertips of one hand, and poor some liquid ground on the middle of it. By turning and moving the plate the liquid will cover the whole surface equally. Only when the naphtha is completely evaporated, the ground is relatively "hard". The layer, however will not be as hard as a real hard ground for line etching, instead being suitable for "soft ground etching" or "vernis mou".
The plate does not have to be "smoked"; a dark pigment has been added to the ground. There is always enough contrast between the etch ground and the drawing.
Irritation can occur if exposed to the skin or lungs as the ground containt natural asphalt.
Wear protective gloves if the etching ground will be heated to more than 95°C (200°F). Ventilation is required to prevent inhalation of harmful fumes.
The ground can be very dangerous when swallowed. If this happens, avoid vomiting, but warn a doctor immediately. Keep out of reach of children.